ENDORSED BY ENDORSED BY 38 / SEEDWORLD.COM FEBRUARY 2019 branching enzymes which caused more resistant starch to be formed.” Increased genomic data decoded by the IWGSC may provide additional information to help breeders develop new high fiber varieties adapted to local environments and farming practices. Bay State Milling and Arista Cereal Technologies have partnered for several years to develop varieties to satisfy both farmers and food companies to build a reliable, resilient and scalable supply chain. Arista is a joint-venture company between Limagrain and CSIRO, Australia’s National Research Agency. The companies began col- laborating on fundamental research in wheat starch 20 years ago and joined their efforts and expertise in 2006 to develop and commercialize wheat with direct consumer health benefits. Behind the Discovery “The publication of the wheat reference genome is the culmination of the work of many individuals who came together under the banner of the IWGSC to do what was considered impossible,” explains Kellye Eversole, IWGSC executive director. “The method of producing the reference sequence and the principles and policies of the consortium provide a model for sequencing large, complex plant genomes and reaffirms the importance of international collaborations for advancing food security.” All data related to the reference genome of bread wheat were released to the scientific community as soon as they became available in January 2017. They have been publicly available without restriction since July 2018. Common bread wheat, Triticum aestivum, has one of the most complex genomes known. There are six copies of each of its 21 chromosomes with an enormous number of near-identical sequences scattered throughout. The first effort to sequence the genome, published in 2012, used an earlier generation of sequenc- ing technology and assem- bled only 5.42 billion bases, approximately one-third of the genome. In comparison, the newly finished genome includes 15 billion bases and covers 94 percent of the total genome. The new information identifies 107,891 high confi- dence genes including their genomic context of regula- tory sequences on bread wheat’s 21 chromosomes. Typically, geneticists sequence genomes by break- ing DNA into small segments, reading them separately and assembling the pieces back together. But if each chromo- some occurs six times, how do they know where to put any given piece? Worse still, 85 percent of wheat’s DNA con- sists of repetitive sequences, so even if geneticists narrow a piece down to the right chromosome, it’s still a chore to work out where exactly it should sit. It’s like solving a giant jigsaw puzzle that depicts the same patch of blue sky three times over. “You have no idea where things go,” says Eversole. “It’s really a miracle that we finished. The genome sequence of maize had a big impact on cre- ating better varieties. The goal now is to build a better wheat breeder’s toolbox and increase profitability for growers.” The sequenced genome comes from Chinese Spring, an unusual variety which few farmers would recognize as wheat. It is historically impor- tant as the foundation of early wheat research. Now that its genome data has been pub- lished, it will be much easier for scientists to sequence a wider range of cultivars and understand the genetic under- pinnings of different traits. “This annotated refer- ence sequence of wheat is a resource that can now drive disruptive innovation in wheat improvement, as this commu- nity resource establishes the foundation for accelerating wheat research and applica- tion through improved under- standing of wheat biology and genomics-assisted breeding,” says Rudi Appels, an AgriBio Research Fellow and pro- fessor at the University of Melbourne and Murdoch University. “Importantly, the bioinformatics capacity devel- oped for model-organism genomes will facilitate a better understanding of the wheat genome as a result of the high-quality chromosome- based genome assembly. “By necessity, breeders work with the genome at the whole chromosome level, as each new cross involves the modification of genome-wide gene networks that control the expression of complex traits such as yield.” Appels says that with the annotated and ordered reference genome sequence, researchers can now access sequence-level information to precisely define the necessary changes in the genomes for breeding. This will be realized through the implementation of new DNA marker platforms and targeted breeding tech- nologies. SW